scsi: g_NCR5380: Autoprobe board IRQ by default

Automatically probe the board irq when no irq parameter is provided, to
simulate PnP. The old default behaviour was to disable the irq.

Update driver documentation accordingly and add some printk messages to
make this behaviour visible.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/g_NCR5380.c

@@ -37,7 +37,7 @@
 #define MAX_CARDS 8
 
 /* old-style parameters for compatibility */
-static int ncr_irq;
+static int ncr_irq = -1;
 static int ncr_addr;
 static int ncr_5380;
 static int ncr_53c400;
@@ -52,9 +52,9 @@ module_param(ncr_53c400a, int, 0);
 module_param(dtc_3181e, int, 0);
 module_param(hp_c2502, int, 0);
 
-static int irq[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
+static int irq[] = { -1, -1, -1, -1, -1, -1, -1, -1 };
 module_param_array(irq, int, NULL, 0);
-MODULE_PARM_DESC(irq, "IRQ number(s)");
+MODULE_PARM_DESC(irq, "IRQ number(s) (0=none, 254=auto [default])");
 
 static int base[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
 module_param_array(base, int, NULL, 0);
@@ -344,6 +344,8 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt,
 	/* Compatibility with documented NCR5380 kernel parameters */
 	if (irq == 255 || irq == 0)
 		irq = NO_IRQ;
+	else if (irq == -1)
+		irq = IRQ_AUTO;
 
 	if (board == BOARD_HP_C2502) {
 		int *irq_table = hp_c2502_irqs;
@@ -370,24 +372,28 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt,
 		magic_configure(port_idx, board_irq, magic);
 	}
 
-	if (irq == IRQ_AUTO)
+	if (irq == IRQ_AUTO) {
 		instance->irq = g_NCR5380_probe_irq(instance);
-	else
+		if (instance->irq == NO_IRQ)
+			shost_printk(KERN_INFO, instance, "no irq detected\n");
+	} else {
 		instance->irq = irq;
+		if (instance->irq == NO_IRQ)
+			shost_printk(KERN_INFO, instance, "no irq provided\n");
+	}
 
 	if (instance->irq != NO_IRQ) {
 		if (request_irq(instance->irq, generic_NCR5380_intr,
 				0, "NCR5380", instance)) {
-			printk(KERN_WARNING "scsi%d : IRQ%d not free, interrupts disabled\n", instance->host_no, instance->irq);
 			instance->irq = NO_IRQ;
+			shost_printk(KERN_INFO, instance,
+			             "irq %d denied\n", instance->irq);
+		} else {
+			shost_printk(KERN_INFO, instance,
+			             "irq %d acquired\n", instance->irq);
 		}
 	}
 
-	if (instance->irq == NO_IRQ) {
-		printk(KERN_INFO "scsi%d : interrupts not enabled. for better interactive performance,\n", instance->host_no);
-		printk(KERN_INFO "scsi%d : please jumper the board for a free IRQ.\n", instance->host_no);
-	}
-
 	ret = scsi_add_host(instance, pdev);
 	if (ret)
 		goto out_free_irq;
@@ -698,7 +704,7 @@ static int __init generic_NCR5380_init(void)
 	int ret = 0;
 
 	/* compatibility with old-style parameters */
-	if (irq[0] == 0 && base[0] == 0 && card[0] == -1) {
+	if (irq[0] == -1 && base[0] == 0 && card[0] == -1) {
 		irq[0] = ncr_irq;
 		base[0] = ncr_addr;
 		if (ncr_5380)